Stretched Swingarm length preference for Sand Dune Riding

Why do you want an extended swingarm? Do you hillshoot with the bike or do extreme hillclimbs or something? If you are doing it simply for a "better ride", you are heading in the wrong direction.

I have ridden my '95 CR500 in Glamis since '97 and can't think of a reason for extending the swingarm, unless you plan to do the "widowmaker" type competition hill climbs. If you are looking for a better ride meaning plusher try adjusting the compression and rebound adjustments or have the shock reworked for your weight and ability (re-spring/re-valve). Not to mention the fact that extending the swingarm will make the bike turn like a big rig.